<!DOCTYPE html>

<html>
    <head>
        <title>Websocket Test</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width">
    </head>
    <body>
        
        <div>
            <input type="text" id="messageinput"/>
        </div>
        <div>
            <button type="button" onclick="openSocket();" >Open</button>
            <button type="button" onclick="send();" >Send</button>
            <button type="button" onclick="closeSocket();" >Close</button>
        </div>
        <!-- Server responses get written here -->
        <div id="messages"></div>
        
        <!-- Script to utilise the WebSocket -->
        <script type="text/javascript">
                        
            var webSocket;
            var messages = document.getElementById("messages");
            
            
            function openSocket(){
                // Ensures only one connection is open at a time
                if(webSocket !== undefined && webSocket.readyState !== WebSocket.CLOSED){
                    writeResponse("WebSocket is already opened.");
                    return;
                }
                // Create a new instance of the websocket
                webSocket = new WebSocket("ws://localhost:8025/websockets/test");
                alert(webSocket);
                
                /**
                 * Binds functions to the listeners for the websocket.
                 */
                webSocket.onopen = function(event){
                    // For reasons I can't determine, onopen gets called twice
                    // and the first time event.data is undefined.
                    // Leave a comment if you know the answer.
                    if(event.data === undefined) 
                        return;

                    writeResponse(event.data);
                };

                webSocket.onmessage = function(event){
                	alert(event.data);
                    writeResponse(event.data);
                };

                webSocket.onclose = function(event){
                    writeResponse("Connection closed");
                };
            }
            
            /**
             * Sends the value of the text input to the server
             */
            function send(){
                var text = document.getElementById("messageinput").value;
                alert(text);
                webSocket.send(text);
            }
            
            function closeSocket(){
                webSocket.close();
            }

            function writeResponse(text){
                messages.innerHTML += "<br/>" + text;
            }
            
        </script>
        
    </body>
</html>